Scemblix (asciminib) received accelerated approval from the Food and Drug Administration (FDA) for the treatment of adults with newly diagnosed Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase.
The approval, according to a notice from the FDA, was based on efficacy data from the ASC4FIRST trial, which included 405 patients with newly diagnosed Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase. Patients in the trial were randomly assigned to receive either Scemblix or investigator-selected tyrosine kinase inhibitor, which included Tasigna (nilotinib), Gleevec (imatinib), Bosulif (bosutinib) or dasatinib.
The main outcome researchers were assessing was major molecular response rate at 48 weeks. The rate of major molecular response at 48 weeks in the study was 68% in patients assigned Scemblix compared with 49% in those assigned the tyrosine kinase inhibitor, with a difference of 19%. When assessing this rate in the tyrosine kinase inhibitor group particularly in those treated with Gleevec, the rate of major molecular response was 69% in the Scemblix arm compared with 40% in the tyrosine kinase inhibitor arm, with a difference of 30%.
Researchers also assessed the incidence of side effects in patients with newly diagnosed and previously treated Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase. The most common side effects in this group, occurring in at least 20% of patients in the study, were rash, musculoskeletal pain, upper respiratory tract infection, fatigue, abdominal pain, headache and diarrhea, according to the FDA’s notice.
Glossary:
Philadelphia chromosome: an abnormal version of chromosome 22 that may cause immature white blood cells to grow uncontrollably and accumulate in the bone marrow and blood.
Chronic phase: early stages of chronic myeloid leukemia during which the number of mature and immature abnormal white cells is higher than normal in the bone marrow and blood, although lower than it would be during the accelerated or blast phase.
Tyrosine kinase inhibitor: a substance that blocks tyrosine kinases, which take part in cell functions such as growth, signaling and division.
The most common laboratory abnormalities in this group, occurring in at least 40% of patients, included decreased leukocyte count (lower than normal number of white blood cells), decrease lymphocyte count (lower than normal levels of lymphocytes in the blood, a type of white blood cell, decreased neutrophil count (a lower than normal number of neutrophils in the blood, a type of white blood cell), decreased platelet count (lower than normal number of platelets, which help with blood clotting) and decreased calcium corrected (a lower than normal level of calcium after accounting for protein in the blood).
The recommended dose of Scemblix, according to the notice, is 80 milligrams taken orally once per day at approximately the same time of day or 40 milligrams taken twice per day orally at approximately 12-hour intervals.
In October 2021, Scemblix was approved by the FDA for the treatment of patients with Philadelphia chromosome-positive chronic myeloid leukemia in the chronic phase who were not tolerant or have had an inadequate response to two or more tyrosine kinase inhibitors.
When findings from the ASC4FIRST trial were presented at the 2024 American Society of Clinical Oncology Annual Meeting, Dr. Jorge E. Cortes, the director of the Georgia Cancer Center at Augusta University, said that Scemblix had the ability to change the treatment paradigm in patients with chronic myeloid leukemia.
“This is the first study to compare a new drug, in this case [Scemblix], with any of the [tyrosine kinase inhibitors] that are approved in the frontline setting of chronic phase [chronic myeloid leukemia],” Cortes said during a press conference. “We demonstrated a statistically superior response in terms of [major molecular response] at 48 weeks, both against [Gleevec] and against all [tyrosine kinase inhibitors], and a safety and tolerability profile that favors [Scemblix] against all of the [tyrosine kinase inhibitors], suggesting that this strong benefit-risk profile may change the treatment paradigm in [chronic myeloid leukemia].”
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